In recent years, liquid crystal displays have been rapidly spread in place of conventional CRT displays, because of their characteristics such as electric power saving, light weight and slimness. As shown in FIG. 9, for example, a general liquid crystal display typically comprises an input-side polarizing plate 102A, an output-side polarizing plate 102B, and a liquid crystal cell 101. In this structure, the polarizing plates 102A and 102B are each so configured that only linearly polarized light having a oscillation surface in a specific oscillation direction can be selectively transmitted, and placed opposite to each other in the crossed-Nicol arrangement so that the respective oscillation directions can be orthogonal to each other. The liquid crystal cell 101 includes a large number of cells corresponding to the pixels and is placed between the polarizing plates 102A and 102B.
Known examples of such a liquid crystal display utilize various driving modes depending on the alignment mode of the liquid crystalline material in the liquid crystal cell. The majority of currently popular liquid crystal displays are classified into TN, STN, VA, IPS, and OCB modes. In particular, VA-mode liquid crystal displays have become widely spread today.
However, liquid crystal displays have a specific problem such as the problem of viewing angle dependency due to the refractive index anisotropy of liquid crystal cells or polarizing plates. In the problem of viewing angle dependency, the image viewed in the front direction of a liquid crystal display differs in color or contrast from that viewed in oblique directions. The problem of viewing angle dependency has become more significant, as larger screen liquid crystal displays have been developed in recent years.
In order to reduce the problem of viewing angle dependency, various techniques have been developed to date. A typical one of such techniques utilizes a retardation film. In the method utilizing a retardation film as shown in FIG. 10, for example, retardation films 103 and 104 each having the desired optical properties are placed between a liquid crystal cell 101 and a polarizing plate 102A, between the liquid crystal cell 101 and a polarizing plate 102B, respectively, so that the problem of viewing angle dependency is reduced. This method has been widely used to produce liquid crystal displays with good viewing angle characteristics in a simple manner, because the problem of viewing angle dependency can be reduced only by incorporating a retardation film 103 into a liquid crystal display.
In a conventional technique as shown in FIG. 11, such a retardation film is generally configured to comprise a certain substrate 105, an alignment layer 106 provided thereon, and a retardation layer 107 that is formed on the alignment layer 106 and includes liquid crystal molecules, wherein the liquid crystal molecules are aligned by the alignment control force of the alignment layer so as to have the desired refractive index anisotropy. Known examples of such a retardation film include: a retardation film disclosed in Patent Document 1 or 2 which includes an alignment layer-carrying substrate and a retardation layer formed thereon and having a cholesterically ordered molecular structure (a birefringent retardation layer); and a retardation film disclosed in Patent Document 3 which includes an alignment layer-carrying substrate and a retardation layer formed thereon and including a disc-like compound (a birefringent retardation layer).
However, the retardation film having such a structure has a problem in which its retardation properties may change when it is used to form a liquid crystal display, although it has the advantage that it can exhibit excellent retardation properties, because liquid crystal molecules are used in it. Specifically, when a retardation film having the structure shown in FIG. 11 is used to form a liquid crystal display, the retardation film has to be bonded to a liquid crystal cell and a polarizing plate (or polarizer) with an adhesive. Therefore, a pressure-sensitive adhesive layer is essentially formed to bond the liquid crystal cell and the polarizing plate (or polarizer) to the retardation film. However, there is a problem in which the adhesive attached to the retardation layer containing a liquid crystalline material and the like may affect and disturb the alignment of liquid crystal molecules in the retardation layer, so that the optical properties of the retardation film may be degraded.
Patent Document 1: Japanese Patent Application Laid-Open (JP-A) No. 03-67219
Patent Document 2: JP-A No. 04-322223
Patent Document 3: JP-A No. 10-312166